Thermostat.



PATENTED AUG. 23, 1904` G. L. WALKER. THERMOSTAT. APPLICATION FILED JULY s1. 190s.

N0 MODEL.

Patented August 23, 1904.

PATENT OEEIcE.

CHARLES LESLIE WALKER, OE HARROIV, ENGLAND.

THERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 768,098, dated August 23, 1904. Application filed J'ulyT 3l, 1903. Serial No. 167,773. (No model.)

To all whom, it Hefty concern.-

Be it known that I, CHARLEsLEsLIE IVALIIER, civil engineer, a subject of the King of Great Britain, residing at the Hut, Mount Park Road, Harrow,in the county of Middlesex, England, have invented certain new and useful Improvements in Thermostats, of which the following is a specification.

The object of this invention is to construct thermostats which are very sensitive to a sudden increase of temperature, but insensible to a slow increase.

According to this invention the thermostat consists of a device in which fluid is forced by the rise of temperature through passages of diiferent areas, so that if the rise of temperature is gradual the displaced iiuid is carried off by the small passage; but if the rise is sudden this passage cannot carry off all of that which is displaced, and so a iiow takes place in the larger passage which may be utilized in closing or breaking an electric circuit for sounding an alarm or performing other like functions. If the increase of temperature is gradual, the iiow through the constricted passage is sufcient to prevent the signal being given when the thermostat is used to operate a signaling device.

The drawing' illustrates one of many ways in which this invention may be carried out.

The drawing is a vertical section.

a is a tube iilled with mercury. At the ends of this tube are other tubes 5 and c. In the tube 6 is a capillary passage (Z, through which the mercury can only flow slowly. In the tube c, the passage in which is not restricted, are the terminals e f of the alarm-circuit. Vhen the mercury reaches the terminal f, the circuit is completed and the alarm given.

For normal rises of temperature the mercury can flow through the capillary passage Z fast enough to prevent a large rise in the tube c; but in the case of a sudden rise the mercury cannot flow fast enough through the passage cZ.

A large' rise therefore takes place in the tube c and the circuit is completed.

The cavity g above the capillary passage (Z is made of such a size that the mercury will reach the terminal f when the temperature has reached any predetermined height, such. as would be caused by a smoldering iire.

As before stated, the thermostat may be employed to sound a fire-alarm, or it may be employed to open sprinklers or perform like functions. l

l/Vhat I claim isl. In a thermostat a chamber completely filled with Huid,two passages of different areas leading from the chamber, the area of the smaller passage being such that a rise of fluid due to the expansion thereof by heat takes place in the larger passage when the rise of temperature is sudden, and devices operated by the thermostat when there is a certain rise of fluid in the passage of larger area.

2. In a thermostat a chamber completely filled with mercury, two passages of different areas leading from the chamber, the area of the smaller passage being such that a rise of mercury due to the expansion thereof by heat takes place in the larger passage when the rise of temperature is sudden, and devices operated by the thermostat when there is a certain rise of mercuryin the passage of larger areas.

3. In a thermostat a chamber completely filled with fluid,two passages of different areas leading from the chamber, the area of the smaller passage being' such that a rise of Huid due to the expansion thereof by heat takes place in the larger passage when the rise of temperature is sudden, a cavity at the top of the smaller passage, and devices operated by the thermostat when there is a certain rise of fluid in the passage of larger area.

CHARLES LESLIE W'ALKER.

Vitnesses:

WILLIAM JOI-IN IVEEKs, HENRY DENIS HosKINs. 

